Unleaded motor fuel



United Snares Patent UNLEADED MOTOR FUEL Robert C. Binuing, and Clifton N. Sechrist, Texas City, Tex., assignors, by mesue assignments, to Standard Oil Company, Chicago, lll., a corporation of Indiana No Drawing. Filed Aug. 26, 1958, Ser. No. 757,203

3 Claims. (Cl. 44-70) This invention relates to a motor fuel of improved octane number. Particularly the invention relates to an unleaded gasoline containing an octane improving component.

The octane race has forced the octane number of motor fuels used in internal combustion engines, which are spark ignited, to the region of 100. Refiuers are now forced to struggle for fractions of an octane number improvement. The octane race is particularly severe on refiners selling unleaded (clear) gasoline i.e. gasoline containing no tetraethyl-lead additive.

An object of the invention is an unleaded gasoline. A particular object is an unleaded gasoline containing an organic octane improving component.

The motor fuel of the invention comprises hydrocarbons boiling over the gasoline range and a low molecular weight fatty acid which contains from 3 to carbon atoms. The motor fuel of the invention generally contains between about 1 and 15 volume percent of the defined acid or mixtures of these acids. More usually the unleaded motor fuel contains between about 2 and 8 volume percent, based on fuel, of the defined acid.

The motor fuel of the invention contains gasoline as the main component. In other words, the main component of the motor fuel consists of hydrocarbons boiling over the gasoline range. The gasoline range broadly extends over the region between about 100 F. to 425 F. It is to be understood that the endpoint of the gasoline component may vary with the particular motor fuel requirements, for example, the endpoint may be as low as 350 F. The hydrocarbons present in the gasoline component may be any of those commonly present in commercial gasoline. The motor fuel may contain in addition to the defined acid and the gasoline hydrocarbons, various additives to improve its stability and decrease corrosivity. Dyes may be present. The motor fuel of the invention is characterized by an absence of tetraethyl-lead additive.

The octane improving component of the motor fuel of the invention may be one or more of the fatty acids containing from 3 to 5 carbon atoms. Examples of these acids are n-propionic acid, methylpropionic acid, n-butyric 2,985,522 Patented May 23, 1961 ice 2 acid, isobutyric acid and methylbutyric acid. branched-chain acids. are preferred.

TESTS 5 The motor fuel of the invention is illustrated by examples showing the blending octane numbers of 4 species of the defined acids. The gasoline component utilized in the illustrative motor fuels was a blending of napthas obtained from catalytic reforming, naphthas obtained from catalytic cracking and butylenedsobutane alkylate. The gasoline component was unleaded. The clear gasoline component had a CFR-R octane number of 97.3 and a CFR-M octane number of 86.3. The illustrative motor fuels consisted of 95 volume percent of the clear gasoline component and 5 volume percent of the particular acid. In order to show the real efiiectiveness of the acids as octane number improvers, the blending octane number of each acid was calculated from the actual octane number of the particular motor fuel. The blending octane numbers for the particular acids of each motor fuel are set out in the table.

The

Table Blending Octane Number Acid OFR-R OFR-M Diff.

The data show that the branched-chain acids are particularly good in sensitivity i.e. the small difiference between the research octane number and the motor octane number. This lack of sensitivity is particularly important today when many automotive engines are knock-prone at high engine speeds.

Thus having described the invention, what is claimed is:

1. An unleaded gasoline containing from about 2 to about 8 volume percent of a branched chain fatty acid having 4-5 carbon atoms.

2. The fuel of claim 1 wherein said acid is isobutyric acid.

3. The fuel of claim 1 wherein said acid is methylbutyric.

References Cited in the file of this patent UNITED STATES PATENTS 

1. AN UNLEADED GASOLINE CONTAINING FROM ABOUT 2 TO ABOUT 8 VOLUME PERCENT OF A BRANCHED CHAIN FATTY ACID HAVING 4-5 CARBON ATOMS. 